The stable genotype has consistent phenotypic performance over environments. The resultant effect of genotype and environment may not be always independent. The stable genotypes can be identified by evaluating them over locations. This is subjected to pooled analysis over environments. Interpretation of genotype x environment interaction (GEI) can be aided by statistical modelling. Models can be linear formulations such as joint regression (Yates and Cochran (1938), Finlay and Wilkinson (1963), Eberhart and Russell (1966) modelling). Modelling GEI in MLTs (Multilocation trials) helps to determine phenotypic stability of genotypes.